1. Field of The Invention
The invention relates to couplings for tubes or pipes. In particular the invention relates to a method of manufacturing push-in tube fittings.
2. Background of The Invention
Quick couplings or push-in tube fittings of the type similar to U.S. Pat. No. 3,884,513 or U.S. Pat. No. 4,013,310 are a fast, convenient way of making leak-proof connections. The coupling is comprised of two main members; a first insert sleeve member having an axial passage and jaws or gripping fingers projecting radially inwardly at one end of the axial passage, and a second member encircling the first member to clamp the jaws or gripping fingers of the first member onto a tube or pipe which is inserted into the axial passage of the first member. In use, any movement of the tube or pipe in a withdrawing direction will cause relative movement of the two members to increase the force exerted by the gripping fingers on the tube or pipe inserted into the coupling.
The conventional method of manufacturing the insert sleeve having gripping fingers and an internal circumferential gripping edge has some deficiencies which prevent the assembled sleeve from having the necessary leak-proof connection. The method of manufacturing such a sleeve is by first forming the gripping edge and then milling longitudinal slots or kerfs in the sleeve to form the fingers. This method, however, leaves burrs on the corners of the gripping edges where the slots are formed; and these burrs can damage the inserted tube. To eliminate the burrs requires an expensive and unreliable deburring step after milling.